In a well-known brake mechanism, a fluid pressure which is combined a M/C pressure generated by depressing a brake pedal and a fluid pressure generated by a brake fluid pressure increasing unit sucking brake fluid from a M/C and pressurizing the brake fluid is supplied to W/Cs such that the W/C pressure becomes higher than the M/C pressure. In this brake mechanism, if pump pressurization is performed when a driver is depressing the brake pedal, the brake fluid is sucked from the M/C by a pressure pump, so that the W/Cs are pressurized. Therefore, the brake pedal is sucked and then the brake depressing of the driver loosens, so that the M/C pressure is decreased. Meanwhile, if a pump pressurization amount is decreased when the driver is depressing the brake pedal, the decrease of the W/C pressure causes the brake fluid to return from the W/Cs to the M/C. Therefore, the brake pedal returns, and then the depressing of the driver becomes strong. Thereby, it is difficult to increase the W/C pressure to an original target W/C pressure.
For this reason, in the background art, if the brake pedal is sucked, based on an operation amount of the brake pedal before the suction, a braking force is fed back, so that the decrease of the braking force is prevented (see JP-A-2008-213601).
However, since the feedback is performed based on the deceleration of a vehicle, the delay of the feedback such as a delay until a change of the W/C pressure is reflected to the deceleration of the vehicle results in a delay of braking. Further, since the operation amount of the brake pedal before the suction is used as a basis, in a case where the driver performs brake operation during the pressurization by the pressure pump, it is difficult to exactly reflect the brake operation. In other words, in a case where the pressurization by the pressure pump and the brake operation of the driver overlap, it becomes difficult to exactly reflect the brake operation.